Combined hydrotreating process and configurations for same

ABSTRACT

At least two feedstocks ( 210 A) ( 210 B) with different boiling point ranges are hydrotreated in an integrated hydrogenation plant ( 200 ) using an interbed separator ( 240 ) that is fluidly coupled between two hydrogenation reactors ( 230 A) ( 230 B). Contemplated configurations and methods will significantly reduce construction and operating cost by integration of at least two hydrogenation processes of two different feedstocks into one process, and/or by providing process conditions that reduce use of catalyst in at least one of the reactors.

FIELD OF THE INVENTION

The field of the invention is petrochemistry, and particularlyhydrotreating of various hydrocarbonaceous feedstocks.

BACKGROUND OF THE INVENTION

Hydrotreating is a type of hydroprocessing commonly used in many modernrefineries, in which hydrogen is contacted in the presence of a catalystwith a hydrocarbonaceous feedstock to remove impurities, includingoxygen, nitrogen, sulfur, and to saturate hydrocarbons. A frequentlyemployed form of hydrotreating is hydrodesulfurization, which is usedprimarily to reduce the sulfur content from refinery intermediatestreams. Hydrodesulfurization is typically used in combination withprocesses including feed pretreatment of catalytic reformers,fluidized-bed catalytic crackers, and hydrocrackers, and may also beused independently as a product quality improvement step for naphtha,diesel, jet, heating oil and residues, saturation of olefins, andpolycyclic aromatics. Hydrocracking is another type of hydroprocessingcommonly used in many modern refineries, in which hydrogen is contactedin the presence of a catalyst with a hydrocarbonaceous feedstock toproduce lighter products (i.e., the average molecular weight decreases).There are numerous hydroprocessing configurations and processes known inthe art, and continuous efforts to reduce energy consumption and capitalcost, while improving product quality, has led to integration ofhydrotreating and hydrocracking reactors in various processes.

For example, in one integration concept, a hydrotreater is combined witha hydrocracker as disclosed in U.S. Pat. No. 3,328,290 to Hengstebeckthat describes a two-stage hydrocracking process wherein fresh feedstockis combined with effluent from the hydrocracking stage and the combinedstreams are then introduced into a hydrotreating stage. A higher-boilingfraction is then separated from the hydrotreater effluent andfractionated to produce a light product and a heavier bottoms stream,which is then recycled with hydrogen-containing gas back to thehydrocracking stage.

Another example U.S. Pat. No. 6,235,190 to Bertram describes anintegrated hydrotreating and hydrocracking process in which twohydrotreating catalysts of different activities are operated in seriesto provide improved product quality, wherein the effluent from ahydrotreating reactor is subjected to a hydrocracking process to convertthe hydrotreated effluent to lighter products with a reduced aromatichydrocarbon content. In a further example, U.S. Pat. No. 6,261,441 toGentry et al., a combined hydrotreating/hydrocracking process isdescribed in which a hydrocracking stage is followed by a hydrodewaxingstage with a single feedstock and a bottoms fraction recycle to producea naphtha product, a distillate boiling above the naphtha range, and alubricant product.

In yet another system, as described in U.S. Pat. No. 6,328,879 toKalnes, two independent feedstocks are hydrocracked in a catalytichydrocracking process that employs a hydrocracking zone, a hydrotreatingzone, and a high pressure product stripper to produce various products,wherein the products have a lower boiling point range than thefeedstocks.

Alternatively, more than one hydrotreater reactor, and or catalyst bedsmay be employed for catalytic hydrogenation as described in U.S. Pat.No. 3,537,981 to Parker, or U.S. Pat. No. 6,103,105 to Cooper. WhileParker's process employs a first hydrotreating reactor coupled to aseparator that is in series with a second hydrotreating reactor, Cooperet al. employ two serially connected hydrotreating catalyst beds withoutthe use of a separator. However, both Coopers and Parkers hydrotreatingconfigurations are typically limited to only a single feedstock.

Thus, although many integrated processes have provided at least someadvantage over other known configurations and methods, all or almost allof the known configurations and methods are limited to processes inwhich hydrocracking is the objective, or in which hydrotreating of asingle boiling range (e.g., naphtha, diesel, gasoil, resid) feedstock isconsidered. Consequently, all or almost all of the known hydrotreatingprocesses require separate plants where more than one feedstock isemployed. Therefore, there is still a need to provide improvedconfigurations and methods for hydrotreating of petroleum products.

SUMMARY OF THE INVENTION

The present invention is directed to configurations and methods forhydroprocessing plants, and especially for integrated hydrotreatingplants in which at least two feedstocks with different boiling pointranges (e.g., gas oil and diesel oil) are hydrotreated. Furtherespecially contemplated aspects include methods for controllingcontemplated configurations.

In one aspect of the inventive subject matter, contemplated plantsinclude an interbed separator that receives a first feed (e.g.,hydrotreated gas oil) and a second feed (e.g., diesel oil), wherein thefirst feed preheats and vaporizes at least part of the second feed,thereby producing a preheated and at least partially vaporized secondfeed, and wherein at least a portion of the first feed is provided by afirst hydrotreating reactor, and wherein at least a portion of thepreheated and at least partially vaporized second feed is fed into asecond hydrotreating reactor that produces a product.

Especially contemplated interbed separators include at least a partialvapor liquid equilibrium stage, preferably at least two vapor liquidequilibrium stages, and may have a configuration of a trayed column or apacked column. It is further preferred that contemplated interbedseparators may receive a hydrogen rich stream, which may be recycled inthe plant, and/or which may be a makeup hydrogen stream. Contemplatedinterbed separators are typically operated at a pressure similar to theoperating reactor pressure of about 500 psi to about 2400 psi.

In particularly preferred aspects of the inventive subject matter, atleast a portion of the second feed is fed into the second hydrotreatingreactor, at a rate effective to control light-end recovery of thehydrotreated first feed in the interbed separator. The remaining portionof the second feed may then be employed to regulate a temperature in thesecond hydrotreating reactor.

In another aspect of the inventive subject matter, first and secondhydrotreating reactors are operated at conditions under which thehydrotreating reactor feed will exhibit less than 10% conversion, andmore preferably less than 8% conversion. Thus, contemplated secondhydrotreating reactors are preferably operated at a pressure of betweenabout 700 psi and about 2400 psi.

Furthermore, it is contemplated that configurations according to theinventive subject matter may be realized in a new plant. However, theinterbed separator and the second hydrotreating reactor may also beintegrated as an upgrade into an existing hydroprocessing plant.

In a further aspect of the inventive subject matter, a method ofhydrotreating includes one step in which a first hydrotreating reactor,a second hydrotreating reactor, and an interbed separator that receivesa first feed and a second feed are provided. In another step, theinterbed separator is fluidly coupled to the first and secondhydrotreating reactors. In a still further step, the hydrotreated firstfeed is used to preheat and vaporize at least part of the second feed,thereby producing a preheated and at least partially vaporized secondfeed, and in another step, at least a portion of the preheated and atleast partially vaporized second feed is mixed with another part of thesecond feed and fed into the second hydrotreating reactor.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view of an exemplary configuration of a prior arthydrotreating plant.

FIG. 2 is a schematic view of an exemplary configuration of ahydrotreating plant according to the inventive subject matter.

FIG. 3 is a schematic detail view of streams relating to the interbedseparator according to the inventive subject matter.

DETAILED DESCRIPTION

Various known configurations and processes for desulfuration and/ordenitrification utilize a process that employs a hydrotreating reactorin which a hydrocarbonaceous feed is reacted with hydrogen in thepresence of a catalyst to form H₂S and/or NH₃ from sulfur-and/ornitrogen-containing compounds in the feedstock. Prior Art FIG. 1 depictsa typical configuration 100 for such plants. Here, a single feedstock(e.g., diesel) 110 is passed through a heater 120 and subsequently fedinto a hydrotreating reactor 130. Hydrogen (separately [via line 141],or in combination [via line 142] with the feedstock) is added to thecatalyst in the hydrotreating reactor and the hydrotreated product 112is (after a cooling step in cooler 180) separated in separator 150 intoa gaseous portion 112A, which predominantly comprises hydrogen, hydrogensulfide, and light non-condensable hydrocarbons and a liquid portion112B, which comprises hydrotreated diesel, some wild naphtha, andremaining sour gas. The hydrogen from the gaseous portion is typicallypurified in an absorber 152 with an amine-containing solvent, andrecycled (supra) into the hydrogen reactor via compressor 160. Thehydrotreated product 112C can then be retrieved from column 170 alongwith typical products such as wild naphtha 112D and sour gas 112E. Whilesuch configurations work relatively well for a single type of feedstock(e.g., vacuum gas oil, gas oil, diesel, naphtha, etc.), known plantswith multiple feedstocks (e.g., gas oil and diesel) generally requiremultiple and separate hydrotreating configurations, which addsignificant cost to construction and operation of such plants.

In their efforts to improve configurations and methods for hydrotreatinghydrocarbonaceous feeds, the inventors have discovered that multiplefeedstocks (ie., feedstocks with different boiling point ranges—e.g.,gas oil and diesel) can be hydrotreated in an integrated configuration,in which an interbed separator is fluidly coupled to a first and asecond hydrotreating reactor, and in which a single hydrogen recyclingloop (e.g., comprising a cooler or heat exchanger, a liquid/gasseparator, an amine stripper, and a compressor) can be employed for two(or more) hydrotreating reactors each treating different feeds.

Consequently, in a particularly preferred aspect of the inventivesubject matter, a plant may comprise an interbed separator that-receivesa first feed and a second feed, wherein the first feed preheats andvaporizes at least part of the second feed, thereby producing apreheated and at least partially vaporized second feed, wherein at leasta portion of the first feed is provided by a first hydrotreatingreactor, and wherein at least a portion of the preheated and at leastpartially vaporized second feed is fed into a second hydrotreatingreactor that produces a product.

FIG. 2 depicts an exemplary configuration of a hydroprocessing plant200, in which two different hydrocarbonaceous feedstocks arehydrotreated using an integrated configuration with a single hydrogenrecycle loop. Here, gas oil 210A (first hydrocarbonaceous feedstock) isheated in heater 220 and then introduced into the hydrotreating reactor230A to produce a hydrotreated product 212 (which is the first feed forthe interbed separator). The hydrotreated product 212 is then fed intothe interbed separator (hot separator) 240. It should be recognized thatthe hydrotreated product 212 may pass through equipment (e.g., heatexchangers, etc.) prior to entering the interbed separator 240. Theinterbed separator 240 also receives diesel feed 210B (the second feedfor the interbed separator, which may be preheated) and which ispreferably at least partially (i.e., at least 10-50%, more typically 50to 80%, most typically, 80 to 100%) in the liquid phase. A vapor feed290, typically hydrogen (or hydrogen-containing) may further be fed intothe interbed separator, wherein the vapor feed may be partially recycledwithin the plant. Alternately, the vapor feed (or hydrogen containingfeed) may be at least in part make-up hydrogen.

Within the separator the second feed is at least partially vaporized (orfurther vaporized) and heated by direct contact with the hydrotreatedproduct 212. Additionally, the interbed separator 240 separates thefeeds into products in which the more volatile components will exit theseparator with the vaporized second feed 201′, and the less volatilecomponents will exit with the somewhat cooled hydrotreated separatorproduct 212′. The interbed separator will include at least a partialvapor liquid equilibrium stage, or more preferably two or more vaporliquid equilibrium stages, and may have a configuration of a trayedcolumn or a packed column. The liquid hydrotreated product 212′ is thenfed into column 270A that separates the liquid hydrotreated product 212′into treated products including but not limited to gas oil, wildnaphtha, and sour gas. The vaporized second feed 210′ is then mixed withadditional diesel feed via line 210B′ and introduced (as combined secondfeed) into the second hydrotreating reactor 230B, which may or may notreceive additional feed streams. It should be appreciated that a portionof the lighter boiling range components will be recovered from the firstproduct 212′ and further hydrotreated in the second reactor.

The so hydrotreated second feed 210″ (here: mostly hydrotreated diesel)is then cooled in cooler 280 and separated in separator 250 into aliquid portion and a gaseous portion (predominantly comprising H₂S,hydrogen, and light non-condensable hydrocarbons). The hydrogen in thegaseous portion can be purified via absorber 252, which may useconventional solvents. The compressor 260 compresses thishydrogen-containing recycle gas stream to a suitable pressure forre-introduction into the system (e.g., at first reactor and/or intofirst feed or feedstock). The liquid portion of the second hydrotreatedfeed 210″ is then fed into column 270B that separates the hydrotreatedproducts into treated products which can include, but are not limitedto, low sulfur diesel, wild naphtha, and sour gas.

As also used herein, the term “interbed separator” refers to a separatorthat is fluidly coupled to at least two hydroprocessing reactors suchthat the interbed separator receives an at least partially hydrotreatedfirst feed and a second feed (which may or may not have been previouslyhydrotreated), wherein first and second feeds have different boilingpoint ranges (e.g., gas oil and diesel oil). Typically, contemplatedinterbed separators are operated hot (i.e., 300 to 750° F.), and it isespecially contemplated that the interbed separator further may receivea vapor or a hydrogen-containing feed.

FIG. 3 depicts an especially preferred configuration of the streamsaround the interbed separator 340 and the second reactor in which aportion 310B′ of the second feed 310B, and an additional third feed 395Cis fed to the second reactor (via combined stream 310′), bypassing theinterbed separator, to produce a hydrotreated product 310″. The rate ofthe substantially liquid phase stream 310B″ (of the second feed) isdetermined to allow for the desired light end recovery from the firsthydrotreated feed stock 312′. The term “light-end recovery” as usedherein refers to the recovery of components in a component-mixture,wherein the boiling point of the components is in the upper third, andmore typically upper fourth (or even higher) of the boiling point rangeof the mixture. The remaining portion of the second feed stock 310B′ maybe additionally preheated in a heat exchanger or heater 310C, beforebeing directed to the second reactor. It should be recognized that thethird feed may be any hydrocarbonaceous feedstock, and may includenaphtha, jet, diesel, or gas oil boiling range material. It should alsobe recognized that additional (forth, fifth, etc.) feed streams can befed to the second reactor, bypassing the interbed separator. In thisexemplary configuration the third feed stock 395C is Cycle Oil from anFCC unit. In this preferred configuration the second reactor operates ata steady feed rate while allowing for good operating flexibility in theoperation of the interbed separator, and good light end recoverycontrol. It should also be recognized that the reactor 330B may operatein a two-phase (vapor/liquid) or preferably trickle flow regime.

To maintain a particular inlet temperature to the second reactor 330B,the feed temperatures of heated streams 310B′ and/or 395C′ can beadjusted via integrated (using internal streams within the plant orstripping or fractionation sections) or external heat sources. Thisability to adjust the feed temperature of the portion of the feed thatbypasses the interbed separator is especially advantageous, sincedirecting a portion of the feed to the second hydrotreating reactor willresolve difficulties associated with the heat balance (e.g., thehydrogen stream 390 would have to be temperature controlled (e.g., ashot hydrogen stripping gas) to circumvent heat imbalance). The amount ofthe second feed that bypasses the interbed separator (e.g., by directfeeding into the hydrotreater downstream of the interbed separator) willalso depend on the relative volumetric rates of the first and secondreactor feed stocks. As the volumetric rate of the second reactor feedincreases, relative to the first reactor feed, the percentage of thesecond reactor feed bypassing the interbed separator will typicallyincrease.

Still further, it should be recognized that the portion of the secondfeed (or an alternate third feed) that bypasses the interbed separator(e.g., via direct feed into the second hydrotreater) may be preheated ortemperature controlled. Consequently, it should be recognized thattemperature control of the portion of the second feed may be employed tocontrol the inlet temperature of the second hydrotreating reactor over arelatively wide range (e.g., +−75 degrees F.). Therefore, the portion ofthe second feed that bypasses the interbed separator may typically be ina range of between about 20 vol % (or less) to about 80 vol % (or more)of the entire volumetric rate of the second feed. Most typically,however, the amount of the portion of the second feed that bypasses theinterbed separator will be about 35-65 vol %. Preferably, the additionalfeeds (third, forth, etc.) will be at least partially liquid phase(below its dew point, prior to the addition of makeup or recycle gas, ifany, at the conditions (temperature and pressure) when first fed intothe recycle loop, or when measured at the reactor inlet temperature, andpressure). Thus, it should be recognized that in some of thecontemplated configurations, and especially in those in which a portionof the second or third feed are in liquid phase and fed into the secondhydrotreating reactor, the second hydrotreating reactor is operated in atwo-phase, or preferably trickle flow regime.

It should further be especially recognized that in preferred aspects ofthe inventive subject matter both hydrotreating reactors are operatedunder conditions effective to reduce the concentration of sulfur- and/ornitrogen-containing compounds in the feeds. Consequently, it should berecognized that in preferred configurations both feedstocks aresubstantially not (L e., less than 10%, more typically less than 8%)converted to lower boiling point products. In particularly preferredaspects, the second feedstock comprises diesel, and the diesel containsafter hydrotreating and column separation less than 50 ppm, morepreferably less than 25 ppm, and most preferably less than 10 ppmsulfur-containing products.

Thus, contemplated configurations may be employed for production of twoproducts having different boiling ranges and different productspecifications. For example, an existing gas oil hydrotreating plantupstream of a FCC unit may be upgraded, with relatively low capitalinvestment, to include a second reactor (or reactor section) forproducing high quality low sulfur diesel fuel. It should be especiallyrecognized that in such configurations the required capacity increasefor the existing heater, heat exchanger train and coolers will bemoderate to insignificant since additional heat can leave the system viathe product from the interbed separator to be used as stripper preheat.

Still further, it should be recognized that the concept of bypassing aportion of the second feedstock around the interbed separator (e.g., byfeeding into the hydrotreater downstream of the interbed separator) mayalso be employed in alternative integrated configurations and methods,and especially contemplated alternative configurations include those inwhich a first hydrocracking reactor is serially coupled to a secondhydrotreating reactor (see e.g., U.S. Pat. No. 6,328,879 to Kalnes,incorporated by reference herein).

Still further, it should be recognized that the concept of bypassing aportion of the second feedstock around the interbed separator may alsobe extended to alternative integrated configurations and methods, andespecially contemplated alternative configurations include those inwhich a first hydrotreating reactor is serially coupled to a secondhydrocracking reactor.

Among other advantages, adding a fluid portion of the third feed to thesecond reactor, without passing through an interbed separator, willallow processing of a higher boiling point range material (i.e. similarto the first feedstock) without loss of the higher boiling rangefraction of the third feedstock in a separator. Moreover, potentialdifficulties associated with the heat balance may be reduced, if notentirely avoided.

It should be especially appreciated that the terms “hydrocracking” and“hydrotreating” are not referring to the same type of hydroprocessoccurring in the reactor. As used herein, the term “hydrocrackingreactor” as used herein refers to a reactor in which ahydrocarbon-containing feed is converted to lighter products (i.e., theaverage molecular weight decreases), wherein the term “conversion” or“converted” means that a particular percentage of fresh feed changes tomiddle distillate, gasoline and lighter products (see e.g.,“Hydrocracking Science And Technology” by J. Scherzer and A. J. Gruia;Marcel Decker, Inc.). Thus, contemplated hydrocracking reactors willhave a conversion of at least 15%, more typically at least 30%, and mosttypically at least 50%. In contrast, the term “hydrotreating reactor”refers to a reactor in which a hydrocarbon-containing feed is reactedwith hydrogen in the presence of a catalyst under conditions that (a)result in less than 15% conversion, and more typically less than 10%conversion, and (b) result in the formation of H₂S and/or NH₃ fromsulfur- and nitrogen-containing compounds in the hydrocarbon-containingfeed.

With respect to the first, second, and third hydrocarbonaceousfeedstocks (210A, 210B, and 395C) it should be appreciated that varioushydrocarbonaceous feedstocks are considered suitable for use herein, andin especially contemplated aspects the first hydrocarbonaceous feedstockcomprises gas oil or any petroleum fraction with a boiling point rangehigher than diesel and the second hydrocarbonaceous feedstock comprisesdiesel, or any fraction with a boiling point range lower than the firstfeedstock. In a still further especially contemplated aspect, the thirdhydrocarbonaceous feedstock may comprise any feedstock regardless ofboiling range. Suitable hydrocarbonaceous feedstocks include crude orpartially purified petroleum fractions, including light gas oil, heavygas oil, straight run gas oil, deasphalted oil, kerosene, jet fuel,cycle oil from an upstream FCC (fluid catalytic cracking) reactor etc.While not limiting to the inventive subject matter, it is generallypreferred that suitable first and second hydrocarbonaceous feedstockshave different boiling point ranges, wherein the first hydrocarbonaceousfeedstock typically has a boiling point range that is higher (at least 5degrees centigrade, more typically at least 10 degrees centigrade, andmost typically at least 25 degrees centigrade as measured from the midvolume boiling point in the boiling point range) than the second boilingpoint range. Suitable first and second feed will typically have at leastone different physicochemical parameter (e.g., molecular composition,boiling point range, etc.). The design rates of the sum of the firstfeedstock to that of the second plus third (plus, fourth, fifth, etc)will typically be such that the sum of the feeds to the first reactor isgreater than the sum of feeds the second reactor. The sum of the feedsrates to the second reactor may typically be in a range of between about25 liquid vol % (or less) when measured at standard conditions to about90 liquid vol % (or more) of the sum of the feed rates to the firstreactor. In the most preferred design the sum of the rates to the secondreactor will be between about 40 liquid vol % to about 80 liquid vol %.

Suitable interbed separators particularly include hot separators,wherein such hot separators are further configured to receive at leastpart of the second feed and possibly a vapor feed, typically hydrogencontaining, which may or may not be optional. In a particularlypreferred alternative aspect of the inventive subject matter, it iscontemplated that the concentration of the hydrogen in thehydrogen-containing feed may vary substantially, and while the hydrogenconcentration in some configurations may be between about 50 vol % and95 vol % (and even more), the concentration of hydrogen may also belower (e.g., between 1 vol % and 50 vol %), or even be substantiallyzero. In such cases, where the hydrogen containing feed is substantiallyfree from hydrogen (i.e., less than 1 vol %), it is preferred that thestream may predominantly comprise light-end-materials (i e., materialsthat will leave the separator as a gaseous component). It is alsorecognized that the vapor feed may be fed from its source withoutadditional preheat. Typically the vapor source will be from a make-upgas compressor, or from a recycle gas compressor. As such thetemperature of the vapor to the interbed separator can be from 80° F. to350° F., more typically be in the range of 125° F. to 300° F., and mosttypically in the range from 150° F. to 275° F. Addition vapor preheat ispossible and advantageous only to the extent that it may improve theplant thermal efficiency, but may also add additional capital cost.

It should be especially recognized that suitable interbed separators arepreferably operated at a pressure that is at or close to the pressure inthe first hydrotreating reactor and at a pressure that is at or abovethe pressure of the second hydrotreating reactor. Consequently, suitableinterbed separators will typically be operated at between about 500-2400psi. However, where suitable it should be appreciated that the pressuremay also be less than 700 psi and especially contemplated lowerpressures are generally between 700 to 400 psi, and even less.Similarly, where hydrotreating conditions allow, interbed separators mayalso be operated at a pressure above 2400 psi, and suitable higherpressures include pressures between 2400 to 4000 psi, and even higher.Due to the relatively high partial pressure of hydrogen in the separator(the hydrogen may be hydrogen that is recycled within the plant), it iscontemplated that the effective hydrocarbon vapor partial pressure isless than 200 psi, and more typically within a range of between about 80psi to 180 psi, and most typically within a range of between about 30psi to 150 psi.

In a particularly contemplated aspect of the inventive subject matter,it is contemplated that the interbed separator is operated such that thetemperature of the hydrogenated product from the first hydrotreatingreactor will evaporate at least part of the second feed. Thus, inespecially preferred configurations, the at least part of thehydrogenated product will be in a gaseous, or vapor phase, and at leastpart of the second feed (e.g., at least 50%, more typically at least75%, even more typically at least 85%, and most typically at least 80%or 100%) will be vaporized by the heat of the first feed. Consequently,it should be appreciated that the energy required to operate the secondhydrotreating reactor will predominantly be provided by the heat andpressure of the first hydrotreating reactor.

With respect to particular temperatures, it is contemplated that thefirst reactor will preferably operate at about 650° F., the interbedseparator will preferably operate at a temperature of between about 650°F. and about 600° F., and the second reactor will preferably operate ata temperature of about 600° F. However, it should be recognized thatdepending on the particular feed of the first and second reactors, thepressures and temperatures may vary accordingly. With respect to thetemperature regulation in the second hydrotreater, it should berecognized that the temperature in the second hydrotreating reactor maybe regulated by feeding at least a portion of the second feed, or anadditional feed to the second reactor.

Additionally, it should be appreciated that the products from the firstreactor (i.e., the first feed) preheat and vaporize at least part of thesecond feed. Consequently, it is contemplated that the so produced vaporwill comprise a portion of one or both feeds (typically in the sameboiling range), and that the so produced vapor is fed in contemplatedconfigurations to the second reactor (which may contain one or morecatalyst beds). It is also contemplated that the liquid remnants fromthe interbed separator first feed, somewhat cooled from vaporizing thesecond feed, can be fed directly to the first feed product stripperwithout additional stripper preheat. It is also contemplated that anintermediate pressure (a pressure set between the operating pressure ofthe interbed separator, and the pressure of the stripper) flash drum inthe feed stream to the stripper may be included to provide a means forsafely letting down the pressure and to recover dissolved hydrogen fromthe stripper feed. It is also contemplated that the liquid remnants fromthe interbed separator first feed stock may pass through equipment otherthan an intermediate pressure flash drum (e.g., heat exchangers, pumps,etc.), en route to the first feed product stripper.

By integration of two hydrotreating reactors into contemplatedconfigurations, costs for construction and operation of contemplatedplants will be significantly reduced. For example, it is contemplatedthat the cost for a hydrogen recycle compressor in contemplatedconfiguration will be substantially lower than the cost for twoindependent recycle compressors. Additionally, it is contemplated that acommon set of fractionation columns (herein referred to as a gas plant)designed to separate light hydrocarbon fractions can be used downstreamof the product stripper columns can be installed for substantially lesscost than for two independent gas plants. In yet another aspect of theinventive subject matter, it should be appreciated that the energyrequired to operate the second hydrotreating reactor will predominantlybe provided by the heat and pressure of the first hydrotreating reactor.Consequently, it is contemplated that a second heater for the secondreactor may be omitted.

Furthermore, it should be recognized that the product of the secondhydrotreating reactor (here: being lower boiling point material) is wellsuited to sponge (i.e., at least partially remove) light hydrocarboncomponents that are not condensable at typical hydrotreating operatingconditions (temperatures and pressures). Removing these non-hydrogencomponents from the recycle gas purifies the hydrogen rich recycle gasto the first reactor section. Compounds that will be removed (sponged bythe products from the second reactor) from the recycle gas includemethane, ethane, propane, and butanes. Purification of the hydrogen richrecycle gas will advantageously remove essentially inert, light endcomponents and increase the hydrogen partial pressure thereby reducingthe size of the equipment(e.g., reactors), and the amount ofhydrotreating catalyst required.

In a still further aspect, it should be recognized that by fluidlycoupling the first reactor to the second reactor, the second reactor isoperating at a significantly higher pressure than a typical standalonedesign designed only to treat the lighter second feed, therebysignificantly reducing the amount of required catalyst for the secondreactor. This reduction in catalyst amount in the second reactor greatlyoffsets the additional costs associated for designing the second reactorat the higher pressure.

Dimensions and capacities of contemplated hydrotreating reactors willtypically depend at least in part on the particular feedstock, and theoverall throughput capacity of the hydrogenation plant. Thus, it iscontemplated that all known hydrotreating reactors are suitable for useherein. Consequently, the nature of the catalyst may vary considerably.However, preferred hydrotreating catalysts may include those comprisingcobalt, molybdenum and/or nickel distributed on a carrier (e.g., aluminaextrudate).

It should also be appreciated that suitable configurations may includeadditional hydrotreating reactors (i.e., a third reactor, a fourthreactor, etc.) and separators, wherein each of the additional reactorsare fluidly coupled to an existing or preceding reactor via a separatorthat receives the product of the existing or preceding reactor, and thatremoves at least one component of an additional feedstock for theadditional reactor. With respect to the components (e.g., piping,hydrotreating reactor, compressor, heat exchanger, etc.) in contemplatedconfigurations, it is contemplated that all known and commerciallyavailable components may be employed. Furthermore, contemplatedconfigurations may be realized in a new plant, however, it is especiallypreferred that a separator and a second hydrotreating reactor areintegrated as an upgrade into an existing hydrotreating plant.

Consequently, a method of operating a plant may comprise a step in whicha first hydrotreating reactor, a second hydrotreating reactor, and aninterbed separator that receives a first feed and a second feed areprovided. In a further step, the interbed separator is fluidly coupledto the first and second hydrotreating reactors. In a still further step,the first hydrotreated feed is used to preheat and vaporize at leastpart of the second feed, thereby producing a preheated and at leastpartially vaporized second feed, and in yet another step, at least aportion of the preheated and at least partially vaporized second feed ismixed with the remaining second feed and is fed into the secondhydrotreating reactor. With respect to the first and secondhydrotreating reactors, the interbed separator, the feeds andfeedstocks, the hydrotreated product, and the hydrotreated product, thesame considerations as described above apply.

Thus, specific configurations and methods of improved hydrotreating havebeen disclosed. It should be apparent, however, to those skilled in theart that many more modifications besides those already described arepossible without departing from the inventive concepts herein. Theinventive subject matter, therefore, is not to be restricted except inthe spirit of the appended claims. Moreover, in interpreting both thespecification and the claims, all terms should be interpreted in thebroadest possible manner consistent with the context. In particular, toterms “comprises” and “comprising” should be interpreted as referring toelements, components, or steps in a non-exclusive manner, indicatingthat the referenced elements, components, or steps may be present, orutilized, or combined with other elements, components, or steps that arenot expressly referenced.

1. A system for integrated hydrotreating of a first and a secondfeedstock with different boiling point ranges, comprising: an interbedseparator that is configured to produce a separator liquid and toreceive a first hydrocarbonaceous feed and a second hydrocarbonaceousfeed, wherein the first feed has a temperature that is effective topreheat and vaporize at least part of the second feed, thereby producinga preheated and at least partially vaporized second feed; wherein thefirst hydrocarbonaceous feed has a higher boiling point range than thesecond hydrocarbonaceous feed; a first hydrotreating reactor configuredto provide the portion of the first feed, and a second hydrotreatingreactor configured to receive at least a portion of the preheated and atleast partially vaporized second feed and to produce a liquid product;and wherein the plant is further configured such that the liquid productand the separator liquid are separately withdrawn from the system. 2.The system of claim 1 wherein the interbed separator comprises at leasta partial vapor liquid equilibrium stage.
 3. The system of claim 1wherein the interbed separator comprises at least two vapor liquidequilibrium stages.
 4. The system of claim 1 wherein the interbedseparator is a trayed column or a packed column.
 5. The system of claim1 wherein the first feed comprises hydrotreated gas oil or cycle oilfrom a fluid catalytic cracking reactor.
 6. The system of claim 1wherein the second feed comprises diesel oil or cycle oil from a fluidcatalytic cracking reactor.
 7. The system of claim 1 wherein theinterbed separator further receives a hydrogen containing stream.
 8. Thesystem of claim 7 wherein the hydrogen containing stream is recycled inthe plant.
 9. The system of claim 7 wherein at least a portion of thehydrogen containing stream is a make-up hydrogen stream.
 10. The systemof claim 1 wherein the interbed separator is operated at a pressure ofbetween about 500 psi to about 2400 psi.
 11. The system of claim 10wherein the second hydrotreating reactor is operated at a pressure ofbetween about 700 psi and about 2000 psi.
 12. The system of claim 1wherein at least a portion of the second feed is fed into the secondhydrotreating reactor.
 13. The system of claim 1 wherein a third feed isfed to the second hydrotreating reactor.
 14. The system of claim 12wherein the portion of the second feed has a temperature effective toregulate a temperature in the second hydrotreating reactor.
 15. Thesystem of claim 12 wherein the portion of the second feed controlsrecovery of a lighter boiling range material from the hydrotreated firstfeed in the interbed separator.
 16. The system of claim 1 wherein theinterbed separator and the second reactor are integrated as an upgradeinto an existing hydroprocessing plant.
 17. The system of claim 1wherein the first hydrotreater receives a first total feed and thesecond hydrotreating reactor receives a second total feed, and whereinthe second total feed is between 25 vol % to 90 vol % of the first totalfeed.
 18. The system of claim 1 wherein the first hydrotreater receivesa first total feed and the second hydrotreating reactor receives asecond total feed, and wherein the second total feed is between 40 vol %to 80 vol % of the first total feed.
 19. A method of hydrotreating atleast two distinct hydrocarbonaceous feeds to form at least two distincthydrotreated products, comprising: providing a first hydrotreatingreactor, a second hydrotreating reactor, and an interbed separator thatreceives a first hydrocarbonaceous feed and a second hydrocarbonaceousfeed, wherein the first hydrocarbonaceous feed has a higher boilingpoint range than the second hydrocarbonaceous feed; fluidly coupling theinterbed separator to the first and second hydrotreating reactors; usingthe first feed to preheat and vaporize at least part of the second feed,thereby producing a preheated and at least partially vaporized secondfeed; and feeding at least a portion of the preheated and at leastpartially vaporized second feed into the second hydrotreating reactor;and separately withdrawing a hydrotreated first hydrocarbonaceous fluidfrom the interbed separator and a hydrotreated second hydrocarbonaceousfluid from the second hydrotreating reactor.
 20. The method of claim 19wherein the first feed comprises a gas oil boiling range material andwherein the second feed comprises a material with a lower boiling rangethan gas oil.
 21. The method of claim 19 wherein the interbed separatoris operated at a pressure of between about 500 psi and about 2400 psi,and wherein the second hydrotreating reactor is operated at a pressureof between about 700 psi and about 2000 psi.
 22. The method of claim 19wherein the second hydrotreating reactor produces a product that spongescomponents from a recycle gas that is created at least in part in thefirst hydrotreating reactor.
 23. A system for integrated hydrotreatingof a first and a second feedstock with different boiling point ranges,comprising: an interbed separator that receives a firsthydrocarbonaceous feed and a second hydrocarbonaceous feed, and thatforms a first hydrotreated liquid, wherein the first feed preheats andvaporizes at least part of the second feed, thereby producing apreheated and at least partially vaporized second feed; wherein the atleast a portion of the first feed is provided by a first hydroprocessingreactor, and wherein at least a portion of the preheated and at leastpartially vaporized second feed is fed into a second hydroprocessingreactor that produces a hydrotreated product; wherein the firsthydrocarbonaceous feed has a higher boiling point range than the secondhydrocarbonaceous feed; wherein at least a portion of the second feed isfed into the second hydroprocessing reactor; and wherein the system isfurther configured to allow separate withdrawal of the firsthydrotreated liquid and the hydrotreated product.
 24. A system forintegrated hydrotreating of a first and a second feedstock withdifferent boiling point ranges comprising: an interbed separator thatreceives a first hydrocarbonaceous feed and a second hydrocarbonaceousfeed, wherein the first feed preheats and vaporizes at least part of thesecond feed, thereby producing a preheated and at least partiallyvaporized second feed; wherein at least a portion of the first feed isprovided by a first hydroprocessing reactor, and wherein at least aportion of the preheated and at least partially vaporized second feed isfed into a second hydroprocessing reactor that produces a product;wherein the first hydrocarbonaceous feed has a higher boiling pointrange than the second hydrocarbonaceous feed; and wherein a third feedis fed into the second hydroprocessing reactor.